Study of Wavelength Dependence of Plasma Collision Dynamics and Ionization Mechanism in Laser Solid Matter Interactions

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This research project will improve the understanding of plasma collision dynamics when high power lasers interact with solid materials. With more than 99.9% of visible matter in the universe known to be in a plasma state, it is important to understand the physics of particle ionization, charge collision, and light propagation and absorption in a plasma. One method for producing and studying plasma in laboratories is using high power lasers. When materials are irradiated by high power lasers, bound electrons in atoms and molecules can be freed (i.e., ionized) and thus plasma is created. Laser-plasma interactions during and after material ionization exhibit a lot of interesting phenomena. For example, free electron acceleration by lasers can produce high-energy radiation such as ultraviolet and x-ray light when the accelerated electrons collide with ions. In this project, the laser wavelength dependence of the plasma collision dynamics in solids will be experimentally and theoretically investigated. This project will also promote basic science education to groups who have been traditionally underrepresented in science by hosting science camps for grandparent-headed families and for middle school students of rural families.Since electron collision plays an important role in plasmas, systematic studies on the electron collision frequency are critical for understanding the laser plasma interaction correctly. In this project, the plasma dynamics in solids under laser irradiation will be experimentally studied by measuring both electron collision times and plasma densities using femtosecond-time-resolved interferometry. In particular, the effect of the driver wavelength on plasma dynamics will be investigated. The experiments will also be benchmarked against computer simulations of laser matter interactions. This research will significantly contribute to furthering understanding of wavelength scaling of the laser matter interaction in solids. Furthermore, this study will impact laser-plasma-based technology such as laser-plasma accelerators and provide guidance for high energy density physics using terawatt and petawatt peak power lasers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.